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Discussion Starter · #1 ·
I put a 98 mark 8 dohc engine in an 03 gt and need to make the motor returnless fuel or the car return fuel. I found an 04 mach 1 fuel rail that is returnlees and need to know if it will fit on the mark 8 dohc to make it returnless. The sale on the fuel rail ends tonight and I need to know before I miss out on the sale. Any ideas ?
 

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you'll need more than the fuel rail, the tank, pump, and ECU have to be dealt with...why you're putting a 280hp engine to replace a 260 one is beyond me...if you use the search at the top right of this page, this is a common thread, good luck
 

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Discussion Starter · #3 ·
I don`t want to make the car a return fuel system if I can make the motor returnless fuel. Converting the car to return fuel is expensive and labor intensive. Seems like an easy answer would be to braze the return fuel line closed to block the return fuel, but I am looking for something better than jury rigging it. The 04 mach 1 has a returnless fuel rail, if it will fit the 98 mark 8 and eliminate the return fuel line then the problem is solved. Not being a ford guy or knowing anything about these motors and fuel syatems, I am at a loss here.
 

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From what I gather, it's not that simple, the ECU is different, the pump is different, the tank would be different...I think your best bet is to convert the system to return style, but yeah it would require all said parts
As a side note, there is a guy on Ebay called "Fullonfab" that sells a kit to convert that engine to carb, it uses a crank fired distributor and makes about 400hp..
To me I'd pull that dohc, get a good 4.6 PI motor and add some trick flow heads..the time and money to do what you are doing will not be worth it IMO
 

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The 04 mach 1 has a returnless fuel rail, if it will fit the 98 mark 8 and eliminate the return fuel line then the problem is solved. Not being a ford guy or knowing anything about these motors and fuel syatems, I am at a loss here.
While I do not know for certain, I would think the Mach 1 rails would work. Why? While the Mark8 does have different heads, The intake ports spacing should be similar (all mod motors share the same piston bore spacing). Since the bore spacing is the same, the distance between the fuel injectors must be the same.

Once possible problem area I can think of would be the mounting bosses. Don't know if these would be the same.

Just wondering when this problem was first discovered? Before or after the new motor was dropped in.

+1 with what the others have said. It does not seem like a good idea to convert a return-less car to a return unless there is absolutely no other way.

As another open, could the fuel pressure sensor be cut off of a GT fuel rail and brazed onto the Mark8 return line? This would block off the return line and give a place to mount the FRP.

Just a thought. If it were me, I would do the Mach 1 fuel rails. Would look much better than anything that could be fabbed on your own.

A 3rd option would be to get a set of aftermarket Cobra fuel rails. They should fit on the Mark8 motor for the same reason that the Mach 1 rails do (common bore spacing).
 

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Discussion Starter · #6 ·
I got the car without a motor, then found a 290 hp 98 mark8 motor with 53,000 for $500. I heard it would work and didn`t want to miss out on a good swap at a good price. I knew there would be a few things to change but I did not realize the return/ returnless problem untill the motor was in.
I found both mach1 and cobra fuel rails. The cobra rail is $50. higher and I did not know which, if either one, would work. I figured if there would be any difference it would probably be the bolt holes to mount them but I really don`t know.
 
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